Mar 7, 2013 8:00am PST
meters under and that's going to squash the air up to half size. and that brings us up to boyle's law. boyle's law named after a dude by the name of robert j. law, okay, we're learning these things, all right? and boyle's law just says that pressure multiplied by volume at any one point will equal pressure times volume at another point. so get twice the pressure, you'll get twice the volume. you'll have half the volume. yeah, what i told twice the pressure will be half the volume. very good, lee, sometimes i goof a rooney a little bit, right gang, but does that make sense gang? so you get twice-- you get twice the pressure that's going to squash that stuff up. so the volume will be half as much, huh? what if you push--so you've got three times the pressure, then the volume will get squashed up to how much? a third. how about--i don't know if you can do this. let me try, seven times the pressure, okay, okay, now i shouldn't say seven, now let's say five times the pressure, a fifth right? how about nine times-- how about--all right, here is for the a students, 7.9 times the pressure...
Mar 5, 2013 8:00am PST
? newton's third law. glass pushes water. how hard? the same. just as hard as if it were--huh? let's try this. okay, one more time. see, the vase like that. this water is pushing down against the side, but the side is pushing back up against the water. how hard? just as if you had all the water right here. so it turns out it really does only depend on the depth. let's see what happens with something like this. narrower, narrower tube. [laughter] and there we have it, gang. and we see what? [laughter] exactly the same pressure. isn't that neat? isn't that neat? you like, huh? mmm. huh, huh? doesn't physics always work? [laughter] yeah. all right. you get the idea. hey, but, you know, this is kind of strange, that a little narrow tube like that can exert just as much pressure on the bottom as a wide one. how can we explain that, gang? let's look at the--this time we have a tube like this. okay? how can the pressure down at the bottom here be just the same as if it were all filled with water? it behaves the same, doesn't it? but there's no water here. it turns out that water pressure acts in all